Vacuum drying cylinder



Dec. 30, 1941. E. G. HUZENLAUB 2,268,486

VACUUM DRYING CYLINDER Filed 0612. 16, 1959 2 Sheets-Sheet l INVENTOR ERICK Go HUZEIUJAUB l WV 90M ATTORNEYS i Dec. 30, 1941. HLJZENLAUB 2,268,486

VACUUM DRYING CYLINDER Filed Oct. 16, 1959 Sheets-Sheet 2 INVENTOR ERICH G. IHJZIQNLAUB BY ATTORNEYS Patented Dec. 30, 1941 Erich Gustav Huzenlaub, Brentford, England Application October 16, 1939, Serial No. 299,748

In Great Britain October 25, 1938 Claims.

This invention relates to improvements in rotary drying cylinders of the vacuum type used for drying cereals including rice in batches in contradistinction to continuous drying, the ob-' ject of the invention being to dry wet grain evenly and as quickly as possible without causing deleterious effects to the dried product and to enable filling, emptying, rotating and cleaning of the aforesaid cylinder to take place in the most effective manner.

Cereals such as rice which have been subjected to a parboiling or steam treatment process are filled into the .dryer with the maximum heat possible so that under vacuum the utmost flush ofi of water vapour is achieved and the grain is then subjected to a heat transfer operation, which maintains the product to be dried at such temperature that moisture under vacuum influence continues to be removable. It has been found that if some cereals and rice in particular are subjected to other forms of intense drying, such as hot air drying the skin, evaporation of the grain is excessive and the moisture internally of the kernel cannot emerge with suilicient speed to keep a uniform degree of moisture latent within the grain body. Bing tailing or transverse cracking results due to contraction of the grain skin about a plastic body. With vacuum drying ideal conditions exist provided always that the residual latent heat removed in vapour production is restored. Since heat conduction in vacuum is negligible it is necessary to provide the maximum contact area for heat transfer to the drying grain.

The present invention seeks to overcome the above disclosed difliculties and to provide the maximum efliciency in heat transfer and vapour removal, and to provide moreover means for vapour removal in which the vapour velocity is so reduced that any tendency of the outlet orifices to clog with the material'dried is reduced to a minimum. The device is also designed so that the least possible time is occupied in filling the interior with the hot grain.

The invention consists in the manufacture of a rotary cylindrical vacuum batch dryer more particularly intended for grain and especially rice characterized that the said drying cylinder is steam jacketted and traversed by a series oi axially arranged steam heating conduits arranged in such manner that a sectional cruciform filling space is provided longitudinally of the cylinder openings for reception and discharge of the material and means for fluid inlet and discharge are aligned with said space.

The invention further comprises ileum blades, which distribute the material being treated towards or away from the inlet or outlet o'riflce or orifices dependent upon the direction of rotation, thus allowing the grain to progress along a 'maximum area of heated surface giving thus the best conditions for heat transfer.

The cylindrical vessel is mounted upon self adjusting rollers with accessory alignment rollers, and is circumferentially wheel driven, the said driving wheel being elastically mounted. Steam admission and vapour and condensed water outlets are provided in the form of axial conduits which as to part are rotary but unguided, the

- stationary connections and appurtenances being supported upon a, universally resisting but ultimately yielding member, connections for steam, water outlet and vacuum withdrawal being accomplished through flexible conduit connections.

To enable a positive condensed water outlet to be provided a series of jackboot buckets or scoops are provided fast with the rotary vessel arranged to collect the condensate at the lowermost part of the vessel and deliver same on further rotation into a tun dish or receiver from whence they flow to a stationary conduit and escape through a steam or like trap to hot well or waste.

In order that the invention shall be more fully understood reference is made to the accompanying drawings wherein:

Figure 1 is a longitudinal part sectional elevation of the invention,

Figure 2 is a part sectional end elevation of gure Figure 3 is a cross section on line A-B of gu e Figure 4 shows detail of vapour outlet channel,-

Figure 5 shows detail of axial conduit support.

In the drawings and referring to Figure 1, I is the drying cylinder proper closed at the end by end tube plates 2 and i-which carry steam tubes 4 arranged in groups as shown in Figures 2 and 3 leaving a cruciform space 5 as shown by dotted line 6. Into the drying cylinder proper I there is an opening or openings I closed by a lid 8 removed by sliding along bars 9 and made tight by operating handle I!) through which grain passes.

On rotation of the dryefby spur wheel II and pinion I 2, the grain is distributed away or towards the opening or openings 1 by helical blades l3 according to the direction of rotation. The vacuum is applied by a vacuum pump or motor, not shown, and led through the non-rotatable V a conduit I 4 supported by support II through the rotatable conduit l6 attached to the steam chest cover l1 and a packing gland It used between the non-rotatable conduits II and the rotatable conduit Ii allowing for rotational and axial movement. It is then led through the end tube plate I to the interior of the drying ylinder proper I where it is applied through dome shaped conduits I! covered with a removable wire mesh II as shown in Figure 4 hooked on books 2! and clamped in position by clamps 22, said dome shaped conduits I! having perforations 23 in the dome and lead radially across end plate I and along the length of the cylinder l and stopping where necessary before opening or opening: I.

The drying cylinder proper I is heated by steam led from some suitable supply through a non-rotatable conduit 24 supported by a support 25 through a conduit 28 attached to the steam chest cover 21 with a packing gland 18 allowing for rotational and axial movement through the steamchest cover 21 to the steam chest 2!, whence the steam traverses along the steam tubes 3 and steam jacket I. to steam chest I.

When this steam condenses it falls to the bottom of the steam jacket 30 and by the mtation of the apparatus twin jackbooi; buckets ll which are operative in either direction collect the water in the toe of the bucket 32, withhold the water in the length of the bucket 33 on further rotation and eventually pour the condensed steam from the lip 34 into a tun dish 35 which is connected to a non-rotary water conduit 36, said conduit 36 leading away to waste. The said Jack booted buckets or scoops," are attached to the whole device being rotated to remove condensed steam. when warm enough the wet grain is filled in, the openings closed and locked. The steam is still on and the apparatus again rotated, this time in such a direction as to spread the grain evenly over the largest conduction area. The vacuum is then applied and after a suitable tim or when a sample taken is as required the rotation is stopped, steam out 01! and vacuum shut, air allowed to enter, openingsuncovered and the device rotated in the opposite direction emptying out the grain, the rotation this time converging all the rice towards the openings.

lhe improvements allow in manufacture use of lighter metallic sections, better support against surge, quick emptying and filling and less chance of vapour born grains clogging up the vacuum intake and at the same time following as nearly as possible Boyle's law allowing for the lowest possible vacuum in the drying chamber. Also due'to a vacuum being non-heat conductive the improvements attain a larger heat conduction surface to the rice yet at the same time allowing all parts to be readily accessible for cleaning purposes and not in the way of falling grain when emptying or filling.

Iclaim:

1. Vacuum drying apparatus comprising a cylinder having tube plates at its ends and tubes extending between them and disposed to'provide a space of cruciform cross section within the cylinder for the material to be dried, steam chests at the ends of the cylinder exteriorly of said tube plates and communicating with the respective ends of said tubes, a steam inlet comrotatable part of the apparatus. The tun dish 35 is covered by me .of a screen 11 to prevmt steamwentering steam chest from blowing the condensed steam out of the jack booted buckets ll or away from the tun dish 35.

The device is supported by flanged engaging and self aligning rollers 38 mounted in tiltable arms 39 of equal length about a pivot ll, said rollers 38 engaging circumferential rails ll fitted external or the steam jacket. There are also rollers 42 engaging the dde of the said circumferential rails II to check excess longitudinal motion.

municating axially with one of said steam chests, a steam condensate outlet leading from the cylinder, mesh covered conduits exposed interiorly of the cylinder and extending radially on the inner side of one of said tube plates and longi- Said supports l5 and 28 carrying the non-rotatable conduits l4 and 24 are alike in dcign. 'lheyincorporate two arms I! pinned to the nonrotating conduit by two pins 44. These anns -tube ll, said bearing collar 53 being attachedto a part of a joist or support hollowed out to allow for movement at the lower end of the support.

The process of drying in th improved dryer according to the invention may be carried out with the aid of the above described apparatus in the following manner.

The device is first warmed up preparatory to receiving the grain by turning on the steam, the

tudinally within the peripheral wall of the cylinder in alinement with the respective portions of said cruciform space, and a suction outlet extending axially through the steam chest at one end of the cylinder and in communication with the inner ends of the radially extending portions of said conduits.

2. Vacuum drying apparatus comprising a cylinder having tube plates at its ends and tubes extending between them and disposed to provide a space of cruciform cross section within the cylinder for the material to be dried. steam chests at the ends of the cylinder exteriorly of said tube plates and communicating with the respective ends of said tubes, asteam inlet oommunicating axially with one of said steam chests. mesh covered conduits exposed interiorly of the cylinder and extending radially on the inner side of one of said tube plates and longitudinally within the peripheral wall of the cylinder in alinement with the respective portions of said.

cruciform space, a suction outlet extending axially through the steam chest at one end of the cylinder and in communication with the inner ends of the radially extending portions of said conduits, and longitudinally divided conduits fixed to the cylinder in radial relation therewith and having twin buckets at their outer ends to receive and retain steam condensate and having twin lips to discharge the condensate at their inner ends upon rotation of the cylinder in either direction, and a receptacle supported in relatively fixed position near the axis of the cylinder to receive the steam condensate from the lips on the inner ends of said buckets.

3. Vacuum drying apparatus comprising 2. cylinder having tube plates closing its ends and tubes extending between said plates and disposed to provide a space of cruciform cross section within the cylinder to receive the material to be dried, a jacket surrounding the cylinder, the cylinder having an opening extending through its peripheral wall and said jacket for the introduction and removal of material, blades extending helically in reverse directions on the inner side of the peripheral wall of the cylinder between the ends of the latter and said opening for distributing the material from said opening toward the ends of the cylinder when the latter is rotated in one direction and for collecting the material toward said opening when the cylinder is rotated in the opposite direction, steam chests fixed to the ends of the cylinder in communication with the ends of said tubes and said jacket, a steam inlet and a condensate outlet connected to one of said chests, condensate collecting conduits in the latter chest and arranged radially on the cylinder to rotate therewith and having twin buckets on their outer ends to collect and retain condensate from said chests and jacket and having twin lips on their inner ends to discharge such condensate, upon rotation of the cylinder in either direction, and a relatively fixed condensate outlet to receive the condensate from said lips, perforated suction conduits extending longitudinally along the inner side of the peripheral wall of the cylinder and radially on the inner side to substantially the center of one Cit of said tube plates in planes which correspond with the cruciform cross section of the space for the material within the cylinder, and a suction outlet coaxial with the cylinder and in communication with the inner ends of the radially extending portions of said suction conduits.

4. In a drying apparatus comprising a drying cylinder having rollers supporting it by its periphery for rotation about its axis, an axial fluid conduit secured thereto, and a second fluid conduit with which said axial fluid conduit has rotatable engagement, a support for said second fluid conduit embodying a strut attached to said second fluid conduit to support it and prevent rotation thereof, and a spring yieldably supporting the strut and elastically supporting said second fluid conduit.

5. In a drying apparatus comprising a drying cylinder having rollers supporting it by its periphery for rotation about its axis, an axial fluid conduit secured thereto, and a second fluid conduit with which said axial fluid conduit has rotatable engagement, a support for said second fluid conduit embodying a strut attached to said second fluid conduit to support it and prevent rotation thereof, means supporting said strut for universal movement, a spring yieldably forcing the strut from said supporting means toward said second fluid conduit, and means for limiting the movement of the strut against the action of the spring and toward said supporting means.

ERICH GUSTAV HUZENLAUB. 

